Optical Scanner Device

ABSTRACT

An optical scanner device, comprising a scanning unit, which casts irradiation light emitted from a light source in an arbitrary direction to scan an observation object, an objective lens system, which converges the irradiation light on the observation object, and a photo-detector unit, which is disposed on an optical axis of the objective lens system to have the irradiation light transmit therethrough, is provided. A position of the irradiation light converged on the observation object is detected based on a position of a light spot of the irradiation light transmitting through the photo-detector unit.

BACKGROUND OF THE INVENTION

The present invention relates to a small-type optical scanner devicehaving a photo-detector unit capable of accurately detecting a positionof a light spot.

Conventionally, a confocal probe device having an optical scanner unitand a confocal optical system has been known. The optical scanner unitcan cast irradiation light (for example, laser light) emitted from alight source onto an observation object and is adapted to scan theobservation object by being driven by a drivable optical fiber and anelectrostatically-actuated mirror. The confocal optical system receivesthe light scanned and reflected on a focal plane of the observationobject and eventually generates a confocal image of the observationobject based on the reflected light. Further, the confocal probe devicedetects a position of a light spot of the emitted light on theobservation object so that a spot on the observation object on which theemitted light is to be cast is controlled based on the actually detectedresult. A following method has been known conventionally as a method todetect the spot to cast the emitted light.

FIG. 6 shows such a conventional optical scanner device 300 having anelectrostaticaly-actuated mirror as a means for casting irradiationlight onto an observation object 315. The optical scanner device 300 isprovided with a mirror unit 302 and an objective lens system 305. Theirradiation light 311 (laser light) is reflected on the mirror unit 302and enters the objective lens system 305. The irradiation light 311entering the mirror unit 302 is a parallel pencil, which is focused onthe observation object 315. (In FIG. 6, a light spot 317 indicates thefocal point.)

The mirror unit 302 includes a base plate, which is not shown, on a sideof a mirror surface in the mirror unit 302 which is opposite to a sidereceiving the irradiation light 311, and drive electrodes are providedon the base plate. By applying voltage to arbitrary electrodes,electrostatic force is generated between the drive electrodes and themirror so that a part of the mirror is attracted by the driveelectrodes, and the mirror surface of the mirror unit 302 is arbitrarilyangled. As the electric capacitance being stored in the drive electrodeswhen the voltage is applied and an inclination angle of the mirror areapproximately linearly-related, the angle of the mirror surface can bedefined by the electric capacitance stored in the drive electrodes.Therefore, a position coordinate of the light spot 317 on theobservation object 315 can be calculated based on the electriccapacitance. An example of such a typical mirror unit which can beelectrostatically actuated is disclosed in Japanese Patent ProvisionalPublication No. 2003-29172.

In the optical scanner device 300 disclosed in the above publication, asthe inclination angle of the mirror surface in the mirror unit 302increases, the relation between the electric capacitance and theinclination angle of the mirror surface becomes nonlinear, thus theinclination angle of the mirror surface cannot be obtained accurately.As a result, a position wherein a control unit of the optical scannerdevice 300 recognizes the light spot 317 should be (which is referred toas a target position) and a position of the actually controlled lightspot 317 are separated as the inclination angle of the mirror surfaceincreases. Therefore, a problem occurs as such the image generated basedon reflection which is not accurately controlled is distorted when theinclination angle of the mirror surface is greater.

In consideration of the above problem, in order to obtain an imagewithout being distorted, it is required to measure the position of thelight spot more stably rather than depending on the inclination angle ofthe mirror unit. Conventionally, a following method has been known as amethod to measure the position of the light spot independently from theinclination angle of the mirror unit.

FIG. 7 shows a conventional optical scanner device 400 to measure aposition of a light spot independently from the inclination angle of themirror unit. The optical scanner device 400 is provided with an opticalfiber 401, an objective lens system 405, a beam splitter 407, aphoto-detector element 409 (for example, a photodiode). The opticalfiber 401 includes a scanner unit 403. It should be noted that theoptical fiber 401 can be driven in arbitrary directions by externalforce to scan the irradiation light 411 and is exchangeable with amirror unit such as one described above as the mirror unit 302.

The scanner unit 403 is driven by a driving means which is not shown tocast irradiated light 411. The irradiated light 411 is emitted from thescanner unit 403 to the objective lens system 405. The irradiated light411 transmitted through the objective lens system 405 injects into thebeam splitter 407, whereby a part of the irradiated light 411 is splitand angled at 90 degrees with respect to the direction of travel toenter the photo-detector element 409. An optical axis of the part of theirradiation light 411′ split from the original irradiation light 411 isreferred to as an optical axis 413′. The remaining part of theirradiated light 411 advances straight to reach an observation object415.

With this configuration, an XYZ coordinate system and its original pointO are defined on the observation object 415 as shown in FIG. 7. That is,an intersecting point of an optical axis 413 and a predeterminedposition of the observation object 415 is defined to be the originalpoint O, and a direction parallel to the optical axis 413 is defined tobe an direction of a Z axis. An X axis and a Y axis are perpendicular toeach other and to the Z axis. Further, a corresponding coordinate systemwith an X′ axis, a Y′ axis, and a Z′ axis and an original point O′ isdefined. That is, an intersecting point of an optical axis 413′ and (anincident surface of) the photo-detector element 409 is defined to be theoriginal point O′, and a direction parallel to the optical axis 413 isdefined to be a direction of the Z′ axis. The X′ axis and the Y′ axisare perpendicular to each other and to the Z′ axis.

A position coordinate (X, Y) of the light spot 417 on the observationobject 415 with respect to the original point O can be obtained bydetecting a position coordinate (X′, Y′) of the light spot 417′ on thephoto-detector element 409 with respect to the original point O′. Thus,a position of the light spot can be measured independently from aninclination angle of a mirror unit.

However, in the optical scanner device 400, the irradiation light 411′split by the beam splitter 407 is received in a position separated fromthe original optical axis 413, therefore, a size of the device itselftends to be larger to include the photo-detector element 409 and otheraccompanying components. Thus, in a small space such as inside a frontend portion of a probe, a smaller optical scanning device capable ofdetecting an accurate position of the light spot has been demanded.

SUMMARY OF THE INVENTION

In consideration of the above circumstance, the present invention isadvantageous in that providing an optical scanner device having adetecting unit to detect a position of light, which is small and capableof detecting a position of a light spot with higher accuracy.

According to an aspect of the present invention, there is provided anoptical scanner device, having a scanner unit, which casts irradiationlight emitted from a light source in an arbitrary direction to scan anobservation object, an objective lens system, which converges theirradiation light on the observation object, and a photo-detector unit,which is disposed on an optical axis of the objective lens system tohave the irradiation light transmit therethrough. A position of theirradiation light converged on the observation object is detected basedon a position of a light spot of the irradiation light transmittingthrough the photo-detector unit.

Optionally, the objective lens system may include a first objective lensunit, which receives the irradiation light from the light source via thescanning unit, and a second objective lens unit, which receives theirradiation light emitted from the first objective lens unit. Thephoto-detector unit may be disposed between the first objective lensunit and the second objective lens unit.

Optionally, the photo-detector unit may include a first photo-detectorelement having light-receiving areas partitioned along a first directionand a second photo-detector element having light-receiving areaspartitioned along a second direction which is a different direction fromthe first direction. The irradiation light transmitting through thefirst objective lens unit may further transmit through the firstphoto-detector element and the second photo-detector element to form alight spot in the first photo-detector element and in the secondphoto-detector element respectively and may enter the second objectivelens unit. The position of the irradiation light converged on theobservation object may be detected based on a position of the light spotof the irradiation light formed in the first photo-detector element anda position of the light spot of the irradiation light formed in thesecond photo-detector element.

Optionally, the first direction and the second direction may beorthogonal to each other.

Optionally, the first photo-detector element may be partitioned in aradial direction, and the second photo-detector element may bepartitioned in a circumferential direction.

Optionally, the first photo-detector element may include light-receivingareas partitioned into concentric circles with a central pointcoinciding the optical axis of the objective lens system, and the secondphoto-detector element may include sector-formed light-receiving areas,of which circumferences coincide with a circumference of one of theconcentric circles in the first photo-detector element having a largestdiameter.

Optionally, the photo-detector unit may be disposed orthogonally withrespect to the optical axis of the objective lens system.

Optionally, the optical scanner device may, further comprise acontrolling system to perform feedback control to arrange the positionof the irradiation light converged on the observation object onto atarget position based on the detected position of the light spot of theirradiation light transmitting through the photo-detector unit.

Optionally, the photo-detector unit may be formed with photodiode madeof semiconductor, which transmits light therethrough and generateselectric current from the light.

Optionally, the first objective lens system, the second objective lenssystem, the first photo-detector element, and the second photo-detectorelement may be integrally coupled to form a light spot position detectorunit.

Optionally, the scanning unit may include a mirror to cast theirradiation light emitted from the light source to scan the observationobject and a driving system to drive the mirror in an arbitrarydirection.

Optionally, the scanning unit may include an optical fiber to cast theirradiation light emitted from the light source to scan the observationobject and a driving system to drive the optical fiber in an arbitrarydirection.

According to another aspect of the present invention, there is provideda light spot position detector unit, having an objective lens system,which converges irradiation light emitted from a light source on anobservation object, and a photo-detector unit, which is disposed on anoptical axis of the objective lens system to have the irradiation lighttransmit therethrough. A position of the irradiation light converged onthe observation object is detected based on a position of a light spotof the irradiation light transmitting through the photo-detector unit.

Optionally, the objective lens system may include a first objective lensunit, which receives the irradiation light from the light source and asecond objective lens unit, which receives the irradiation light emittedfrom the first objective lens unit. The photo-detector unit may bedisposed between the first objective lens unit and the second objectivelens unit.

Optionally, the photo-detector unit may include a first photo-detectorelement having light-receiving areas partitioned along a first directionand a second photo-detector element having light-receiving areaspartitioned along a second direction which is a different direction fromthe first direction. The irradiation light transmitting through thefirst objective lens unit may further transmit through the firstphoto-detector element and the second photo-detector element to form alight spot in the first photo-detector element and in the secondphoto-detector element respectively and may enter the second objectivelens unit. The position of the irradiation light converged on theobservation object may be detected based on a position of the light spotof the irradiation light formed in the first photo-detector element anda position of the light spot of the irradiation light formed in thesecond photo-detector element.

Optionally, the first direction and the second direction may beorthogonal to each other.

Optionally, the first photo-detector element may be partitioned in aradial direction, and the second photo-detector element is partitionedin a circumferential direction.

Optionally, the first photo-detector element may include light-receivingareas partitioned into concentric circles with a central pointcoinciding the optical axis of the objective lens system, and the secondphoto-detector element may include sector-formed light-receiving areas,of which circumferences coincide with a circumference of one of theconcentric circles in the first photo-detector element having a largestdiameter.

Optionally, the photo-detector unit may be disposed orthogonally withrespect to the optical axis of the objective lens system.

Optionally, the photo-detector unit may be formed with photodiode madeof semiconductor, which transmits light therethrough and generateselectric current from the light.

Optionally, the first objective lens system, the second objective lenssystem, the first photo-detector element, and the second photo-detectorelement may be integrally coupled.

According to another aspect of the present invention, there is provideda confocal probe comprising an optical scanner device which includes ascanning unit, which casts irradiation light emitted from a light sourcein an arbitrary direction to scan an observation object, an objectivelens system, which converges the irradiation light on the observationobject and a photo-detector unit, which is disposed on an optical axisof the objective lens system to have the irradiation light transmittherethrough. A position of the irradiation light converged on theobservation object is detected based on a position of a light spot ofthe irradiation light transmitting through the photo-detector unit.

According to another aspect of the present invention, there is provideda confocal probe comprising a light spot position detector unit whichincludes an objective lens system, which converges irradiation lightemitted from a light source on an observation object, and aphoto-detector unit, which is disposed on an optical axis of theobjective lens system to have the irradiation light transmittherethrough. A position of the irradiation light converged on theobservation object is detected based on a position of a light spot ofthe irradiation light transmitting through the photo-detector unit.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIG. 1 shows an optical scanner device with photo-detector elementsarranged on an optical axis thereof according to a first embodiment ofthe present invention.

FIG. 2 shows a control flow of the optical scanner device according tothe first embodiment of the present invention.

FIG. 3 shows a perspective view of a light spot position detector unitof the optical scanner according to the embodiments of the presentinvention.

FIG. 4 shows a side view of the light spot position detector unit shownin FIG. 3 according to the embodiments of the present invention.

FIG. 5 shows an optical scanner device with photo-detector elementsarranged on an optical axis thereof according to a second embodiment ofthe present invention.

FIG. 6 shows a conventional optical scanner device with a photo-detectorelement having an electrostatically actuated mirror unit as a means toscan irradiation light.

FIG. 7 shows a conventional optical scanner device to measure a positionof a light spot independently from an inclination angle of a mirrorunit.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, referring to the accompanying drawings, embodiments of thepresent invention will be described.

First Embodiment

FIG. 1 shows an optical scanner device 100 with photo-detector elementsarranged on an optical axis thereof according to a first embodiment ofthe present invention. The optical scanner device 100 includes anoptical system 50 and a control system 60 (see FIG. 2). The opticalsystem 50 includes a light source 150, a mirror unit 102, a light spotposition detector unit 110. The control system 60 includes a controlunit 125. The light spot position detector unit 110 is provided with anobjective lens system 105, a photo-detector element 119, and aphoto-detector element 121. It should be noted that an optical axis ofthe objective lens system 105 is also referred to as an optical axis 113of the optical scanner device 100.

The mirror unit 102, the objective lens system 105, the photo-detectorelement 119, and the photo-detector element 121 are respectivelyarranged on the optical axis 113. In the optical scanner device 100,irradiation light 111 such as laser beam supplied from the light source150 is a parallel pencil, which enters the mirror unit 102 and isreflected thereby to enter the objective lens system 105. It should benoted that the mirror unit 102 is adapted to be arbitrarily driven toscan the irradiation light 111 by adjusting a reflection angle of theirradiation light 111.

The objective lens system 105 is a lens system configured with aplurality of lenses and optical elements and is adapted to converge theirradiation light 111 as a parallel pencil to have a diameter of itsspot to be approximately 1 μm on an observation object 115. With theabove configuration, an orthogonal coordinate system as shown in FIG. 1is defined on the observation object 115. That is, an intersecting pointof the optical axis 113 and the observation object 115 is defined to bean original point O, while a direction parallel to the optical axis 113is defined to be a direction of a Z-axis. Further, an X-axis and aY-axis are respectively defined to be orthogonal to each other and tothe Z-axis as shown in FIG. 1. The irradiation light 111 is converged toform a light spot 117 by power of the objective lens system 105 on aplane being defined by the X-axis and the Y-axis and passing through theoriginal point O. In the present embodiment of the invention, it isconfigured such that a central point 131 of the mirror unit 102corresponds to a focal position of the objective lens system 105. Thatis, the positional relation configures an image side telecentric opticalsystem, and the irradiation light 111 transmitted through the objectivelens system 105 travels in parallel with the optical axis 113.Therefore, the irradiation light 111 reflected by the mirror unit 102can be constantly converged on the plane defined by the X-Y axes andpassing through the original point O.

The photo-detector element 119 and the photo-detector element 121 arerespectively arranged such that light receiving surfaces thereof aresubstantially perpendicular to the optical axis 113 and each centralpoint of the light receiving surfaces coincides with the optical axis113. That is, in the present embodiment of the invention, a position(i.e., an X coordinate, a Y coordinate) of the light spot 117 on theobservation object 115 can be detected based on positions of theirradiation light 111 entering the photo-detector element 119 and thephoto-detector element 121.

The photo-detector elements will be described further in detail. In thepresent embodiment, it is assumed that transparent light-receivingelements made of semiconductor as disclosed in, for example, JapanesePatent Provisional Publication No. H11-312821, are used as thephoto-detector elements 119, 121. Each of the semiconductorlight-receiving elements absorbs a minor part of light received thereonand transmits a major part of the received light to a rear side thereof.Further, the semiconductor light-receiving elements generate electricalcurrent (i.e., photo-electric current) by absorbing the light. Thesemiconductor light-receiving elements are, for example, photodiodesformed by p-n junction and to be substantially thin to transmit thelight therethrough.

The photo-detector element 119 is partitioned into a plurality ofpieces, which are evenly aligned orthogonally with respect to thedirection of the X-axis (i.e., in parallel with the Y-axis). Each of thepieces is connected with an electrode (not shown). As the irradiationlight 111 transmits through the photo-detector electrode 119, it isdetermined in which electrode the photo-electrode current is generated.Thus, a position of the light spot 117 a with respect to the X-axis isdetected, and an X coordinate of the light spot 117 on the observationobject 115 can be obtained. That is, in the present embodiment, as theirradiation light 111 transmitted through the objective lens system 105is parallel to the optical axis 113, the X coordinate detected in thephoto-detector element 119 based on the position of the light spot 117 ais determined to be an X coordinate of the light spot 117.

The photo-detector element 121 is partitioned into a plurality ofpieces, which are evenly aligned orthogonally with respect to thedirection of the Y-axis (i.e., in parallel with the X-axis). Each of thepieces is connected with an electrode (not shown). As the irradiationlight 111 transmits through the photo-detector electrode 121, it isdetermined in which electrode the photo-electrode current is generated.Thus, a position of the light spot 117 b with respect to the Y-axis isdetected, and a Y coordinate of the light spot 117 on the observationobject 115 can be obtained based on the position of the light spot 117 band a distance between the optical axis 113 and the irradiation light111. If the irradiation light 111 transmitted through the objective lenssystem 105 is not parallel with the optical axis 113 and is disposed ata predetermined angle from the optical axis 113, the X coordinate of thelight spot 117 can be geometrically detected based on the predeterminedangle, the X coordinate of the light spot 117 a on the photo-detectorelement 119, and a distance on the Z-axis between the photo-detectorelement 119 and the observation object. Similarly, the Y coordinate ofthe light spot 117 can be detected. However, it should be noted thatlarger detectable areas on the photo-detector elements 119, 121 areavailable when the mirror unit 102 and the objective lens system 105 areconfigured in the image side telecentric optical system so that theirradiation light 111 and the optical axis 113 are maintained parallelto each other. Further, with this configuration, higher resolution fordetecting the position can be achieved. It should be noted, if theirradiation light 111 is not parallel with the optical axis 113,available incident ranges of the photo-detector elements 119, 121 arerestricted, and the diameters of the light spots 117 a, 117 b on therespective detector elements 119, 121 become greater, and the X-Ycoordinates of the light spot 117 may not be accurately detected.

Thus, according to the present embodiment, with the transparentlight-receiving element which transmits irradiation light therethrough,at least one photo-detector element can be arranged on the optical axis113 of the objective lens system 105. Thus, a simpler configuration fordetecting the position of the light spot 117 compared to a conventionaldetecting method using the beam splitter can be achieved is available,and detecting with higher accuracy is achievable.

Next, control taken by the optical scanner device 100 will be described.

The control unit 125 includes a control circuit 127 and a drive circuit129. The control circuit 127 is adapted to obtain signals which indicatethe X-Y coordinates detected by the photo-detector elements 119, 121 andto control the drive circuit 129. The drive circuit 129 is adapted todrive a driving unit 123 based on control by the control circuit 127.The driving unit 123 electrostatically drives the mirror unit 102 aboutthe central point 131 of the mirror unit 102 in, for example, theaforementioned conventional method using electrostatic force. It shouldbe noted that in the present invention an optical fiber can be used tocast the irradiation light 111 for scanning the observation object 115in place of the mirror unit 102.

FIG. 2 shows a control flow of the optical scanner device 100 accordingto the first embodiment of the present invention. First, in the opticalsystem 50, the irradiation light 111 is emitted from the light source150 to the mirror unit 102 (Step 1). Meanwhile, in the control system60, the control unit 125 transmits driving signals indicating thecoordinates of the light spot 117 (target coordinates (X1, Y1)) to bescanned to the control circuit 127 (Step 2). The control circuit 127determines an inclination angle of the mirror unit 102 based on thetarget coordinates based on the driving signals and transmitscorresponding controlling signals to the drive circuit 129 (Step 3). Thedrive circuit 129 inclines the mirror unit 102 according to thecontrolling signals (Step 4). The inclined mirror unit 102 reflects andemits the irradiation light at a predetermined angle to the objectivelens system 105 (Step 5). The irradiation light 111 passed through theobjective lens system 105 further transmits through the photo-detectorelement 119, and thereby the X coordinate of light spot 117 a in thephoto-detector element 119 is detected (Step 6). Similarly, the Ycoordinate of the light spot 117 b in the photo-detector element 121 isdetected (Step 7). Based on the detected X-Y coordinates, X-Ycoordinates (X2, Y2) of the position of the actual light spot 117 on theobservation object are determined by the control circuit 127. Further,modified controlling signals wherein the difference between the targetcoordinates (X1, Y1) and the actually detected coordinates (X2, Y2) ismodified so that the coordinates (X2, Y2) correspond to the targetcoordinates are transmitted to the drive circuit 129 (Step 8).Thereafter, the drive circuit 129 inclines the mirror unit 102 accordingto the modified controlling signals (Step 9).

The process including Steps 5 through 9 is repeated until the targetcoordinate (X1, Y1) and the detected coordinates (X2, Y2) coincide.Thus, the control unit 125 of the optical scanner device 100 canaccurately control the position of the light spot 117 to coincide thetarget coordinates by the feedback control based on the detected resultsobtained by the photo-detector element 119 and the photo-detectorelement 121.

Next, a configuration of the light spot position detector unit 110 ofthe optical scanner device 100 according to the first embodiment of thepresent invention will be described in detail. FIG. 3 shows aperspective view of the light spot position detector unit 110 accordingto the first embodiment of the invention. FIG. 4 shows a side view ofthe light spot position detector unit 110 according to the first and thesecond embodiments of the invention.

The light spot position detecting unit 110 is configured with theobjective lens system 105 a, the photo-detector element 119, a glassplate 131, the photo-detector element 121, and an objective lens system105 b. The objective lens system 105 a is arranged on an incident sideof the light spot position detector unit 110, and the objective lenssystem 105 b is arranged on an ejection side of the light spot positiondetector unit 110. Each of the objective lens systems 105 a, 105 b isconfigured with a plurality of lenses, (however, for example, each ofthe objective lens systems 105 a, 105 b may be configured with a singlelens) and with the objective lens systems 105 a, 105 b, the irradiationlight being a parallel pencil is converged on the observation object115. More specifically, the objective lens system 105 a is configured tobe as an image side telecentric optical system, while the objective lenssystem 105 b is configured to be a system to converge the irradiationlight which is a parallel pencil.

The photo-detector element 119 includes partitioned laminate portions119 a, each of which is made of a transparent semiconductor element, andelectrodes 119 b, each of which is connected with one of the laminateportions 119 a. The photo-detector element 121 is configured similarlyto the photo-detector element 119, however, a direction along which thelaminated portions 121 a are partitioned is different from that of thelaminated portions 119 a. The objective lens system 105 a is coupled toone side of the photo-detector element 119, and the other side of thephoto-detector element is coupled to one side of the glass plate 131.The other side of the glass plate 31 is further coupled to one side ofthe photo-detector element 121, and the other side of the photo-detectorelement 121 is coupled to one side of the objective lens system 105 b.Thus, the irradiation light 111 emitted via the mirror unit 102 istransmitted through the objective lens system 105 a, the photo-detectorelement 119, the glass plate 131, the photo-detector element 121, andthe objective lens system 105 b respectively. In the present embodiment,the irradiation light 111 entering the light spot position detector unit110 is a parallel pencil having a diameter of approximately 200 μm, anda diameter of the light spot on the observation object 115 isapproximately 1 μm. Diameters of the objective lens systems 105 a, 105 bare approximately 1.0-1.5 mm, and a linear range to be scanned by themirror unit 102 is approximately from 250 μm to 400 μm.

It should be noted that as the light spot position detector unit 110 isassembled integrally with the optical components of the objective lenssystems 105 a, 105 b and the photo-detector elements 119, 121 beingcoupled to one another via the glass plate 131, the light spot positiondetector unit 110 can be configured to be smaller. Further, as the lightspot position detector unit 110 is integrally assembled, procedures forcorrectly aligning the optical components and the photo-detectorelements with respect to the optical axis can be omitted, therefore, thelight spot position detector unit 110 can be easily assembled and thepositions of the components can be easily adjusted. Further, with thephoto-detector elements 119, 121, the spot positions of the irradiationlight 111 are directly detected, the positions can be detected withhigher accuracy compared to the conventional detecting method dependingon the inclination angle of the mirror unit as a scanning means.

As above, the optical scanner device 100 to obtain the position of thelight spot 117 in the X-axis direction and the Y-axis direction based onthe orthogonal coordinate system has been described.

Second Embodiment

Next, an optical scanner device 200 to obtain a position of a light spotbased on a polar coordinate system (r, θ) according to a secondembodiment of the present invention will be described.

FIG. 5 shows an optical scanner device 200 with photo-detector elementsarranged on an optical axis thereof according to a second embodiment ofthe present invention. In the present embodiment, description of aconfiguration being similar to the configuration described in the firstembodiment will be omitted. The optical scanner device 200 includes anoptical system 51 (see FIG. 2) having an optical fiber unit 201, a lightspot position detector unit 210, and a control system 61 (see FIG. 2)having a control unit 225. The light spot position detector unit 210includes an objective lens system 205, a photo-detector element 219, anda photo-detector element 221. It should be noted that an optical axis ofthe objective lens system 205 is referred to as an optical axis 213 ofthe optical scanner device 200. The optical fiber unit 201 includes ascanning unit 203, which is adapted to be arbitrarily driven to scanirradiation light 211 (for example, laser beam) emitted from a lightsource 150 (see FIG. 2) on the observation object 217.

Each of the scanning unit 203, the objective lens unit 205, thephoto-detector element 219, and the photo-detector element 221 isarranged on the optical axis 213. In the optical scanner device 200, theirradiation light 211 supplied from the light source 150 is a parallelpencil, which is emitted from the scanning unit 203 of the optical fiberunit 201 and enters the objective lens unit 205. The scanning unit 203is capable of adjusting an ejection angle of the irradiation light 211to cast, and it should be noted that the scanning unit 203 servessubstantially equivalently to the mirror unit 102 in a way to cast theirradiation light 211 on the observation object 215 in arbitrarydirections. The objective lens system 205 functions substantiallyequivalently to the objective lens system 105 of the optical scannerdevice 100, and description of that will be omitted.

The optical axis 213, an XYZ coordinate system, and an original point Oof the XYZ coordinate system are defined similarly to the firstembodiment. Further, for polar coordinates, a length r of a lineperpendicular from a target coordinates (X1, Y1) to the optical axis 213and an angle θ between the perpendicular line and an X-Y plane definedby the X axis and the Y axis are defined.

The photo-detector element 219 is partitioned into a plurality ofring-shaped areas, which are for example evenly divided in radialdirections, with their central points coinciding the optical axis 213.Each of the partitioned ring-shaped areas is connected with an electrode(not shown). The electrodes may be, for example, substantially thin ortransparent electrodes generally used in LCDs (liquid crystal display).As the irradiation light 211 transmits through the photo-detectorelement 219, it is determined in which electrode photo-electrode currentis generated. Thus, an r coordinate of the light spot 217 a in thephoto-detector element 219 can be detected.

The photo-detector element 221 is partitioned into a plurality ofsector-formed areas, which are for example evenly divided in theircircumferential direction. A circumference including the sector-formedareas coincides a circumference of one of the ring-shaped areas having alargest diameter. Each of the sector-formed areas is connected with anelectrode (not shown). As the irradiation light 211 transmits throughthe photo-detector element 221, it is determined in which electrodephoto-electrode current is generated. Thus, a θ coordinate of the lightspot 217 b can be detected.

The control unit 225 includes a control circuit 227 and a drive circuit229. The scanning unit 203 of the optical fiber unit 201 is arbitrarilydriven by a driving unit 223.

In the optical scanner device 200 having the photo-detector element 219and the photo-detector element 221, each of which is partitioned alongan axial direction of the polar coordinate system (r, θ), controlsimilar to the control taken in the optical scanner device 100 in thefirst embodiment is performed. However, as the coordinates detected inStep 6 and Step 7 in the second embodiment are in the polar coordinatesystem, Step 8 is different in that the detected polar coordinates arerespectively converted to X-Y coordinates, and the correspondingposition is considered to be the position of the light spot 217.Thereafter, modified controlling signals are transmitted to the drivecircuit 229.

As above, by arranging the photo-detector elements configured withsemiconductor light-receiving elements which transmit lighttherethrough, a position of the light spot can be detected withouthaving the irradiation light split from the optical axis. Thus, aposition of the light spot can be accurately controlled.

A configuration of a light spot position detector unit 210 of theoptical scanner device 200 in the second embodiment is similar to thatof the light spot position detector unit 110 of the optical scannerdevice 100 in the first embodiment. Therefore, detailed description ofthat will be omitted.

Although examples of carrying out the invention have been describedabove, the present invention is not limited to the above describedembodiments. For example, in the light spot position detector units 110,210 shown in FIGS. 3 and 4, the objective lens systems 105 a, 105 b areemployed, however, the number of the objective lens system may be one,i.e., solely either one of the objective lens system 105 a, 105 b may beemployed (in this case, even with one objective lens system, the lightspot detector unit can function substantially as shown in the opticalscanner devices shown in FIGS. 1 and 5). For another example, there maybe provided solely one photo-detector element, which is partitioned ingrid to detect a position of the light spot that transmits therethrough.Further, the one photo-detector element may be partitioned into ringsand sectors.

The present disclosure relates to the subject matter contained in PCTapplication No. PCT/JP2005/019667, filed on Oct. 26, 2005, which relatesto the subject matter contained in Japanese Patent Application No.2004-316106, filed on Oct. 29, 2004, which are expressly incorporatedherein by reference in its entirety.

1. An optical scanner device, comprising: a scanning unit, which castsirradiation light emitted from a light source in an arbitrary directionto scan an observation object; an objective lens system, which convergesthe irradiation light on the observation object; and a photo-detectorunit, which is disposed on an optical axis of the objective lens systemto have the irradiation light transmit therethrough, wherein a positionof the irradiation light converged on the observation object is detectedbased on a position of a light spot of the irradiation lighttransmitting through the photo-detector unit.
 2. The optical scannerdevice according to claim 1, wherein the objective lens system includesa first objective lens unit, which receives the irradiation light fromthe light source via the scanning unit, and a second objective lensunit, which receives the irradiation light emitted from the firstobjective lens unit; and wherein the photo-detector unit is disposedbetween the first objective lens unit and the second objective lensunit.
 3. The optical scanner device according to claim 2, wherein thephoto-detector unit includes a first photo-detector element havinglight-receiving areas partitioned along a first direction and a secondphoto-detector element having light-receiving areas partitioned along asecond direction which is a different direction from the firstdirection; wherein the irradiation light transmitting through the firstobjective lens unit further transmits through the first photo-detectorelement and the second photo-detector element to form a light spot inthe first photo-detector element and in the second photo-detectorelement respectively and enters the second objective lens unit; andwherein the position of the irradiation light converged on theobservation object is detected based on a position of the light spot ofthe irradiation light formed in the first photo-detector element and aposition of the light spot of the irradiation light formed in the secondphoto-detector element.
 4. The optical scanner device according to claim3, wherein the first direction and the second direction are orthogonalto each other.
 5. The optical scanner device according to claim 3,wherein the first photo-detector element is partitioned in a radialdirection, and the second photo-detector element is partitioned in acircumferential direction.
 6. The optical scanner device according toclaim 5, wherein the first photo-detector element includeslight-receiving areas partitioned into concentric circles with a centralpoint coinciding the optical axis of the objective lens system, and thesecond photo-detector element includes sector-formed light-receivingareas, of which circumferences coincide with a circumference of one ofthe concentric circles in the first photo-detector element having alargest diameter.
 7. The optical scanner device according to claim 1,wherein the photo-detector unit is disposed orthogonally with respect tothe optical axis of the objective lens system.
 8. The optical scannerdevice according to claim 1, further comprising a controlling system toperform feedback control to arrange the position of the irradiationlight converged on the observation object onto a target position basedon the detected position of the light spot of the irradiation lighttransmitting through the photo-detector unit.
 9. The optical scannerdevice according to claim 1, wherein the photo-detector unit is formedwith photodiode made of semiconductor, which transmits lighttherethrough and generates electric current from the light.
 10. Theoptical scanner device according to claim 3, wherein the first objectivelens system, the second objective lens system, the first photo-detectorelement, and the second photo-detector element are integrally coupled toform a light spot position detector unit.
 11. The optical scanner deviceaccording to claim 1, wherein the scanning unit includes a mirror tocast the irradiation light emitted from the light source to scan theobservation object and a driving system to drive the mirror in anarbitrary direction.
 12. The optical scanner device according to claim1, wherein the scanning unit includes an optical fiber to cast theirradiation light emitted from the light source to scan the observationobject and a driving system to drive the optical fiber in an arbitrarydirection.
 13. A light spot position detector unit, comprising: anobjective lens system, which converges irradiation light emitted from alight source on an observation object; and a photo-detector unit, whichis disposed on an optical axis of the objective lens system to have theirradiation light transmit therethrough, wherein a position of theirradiation light converged on the observation object is detected basedon a position of a light spot of the irradiation light transmittingthrough the photo-detector unit.
 14. The light spot position detectorunit according to claim 13, wherein the objective lens system includes afirst objective lens unit, which receives the irradiation light from thelight source, and a second objective lens unit, which receives theirradiation light emitted from the first objective lens unit; andwherein the photo-detector unit is disposed between the first objectivelens unit and the second objective lens unit.
 15. The light spotposition detector unit according to claim 14, wherein the photo-detectorunit includes a first photo-detector element having light-receivingareas partitioned along a first direction and a second photo-detectorelement having light-receiving areas partitioned along a seconddirection which is a different direction from the first direction;wherein the irradiation light transmitting through the first objectivelens unit further transmits through the first photo-detector element andthe second photo-detector element to form a light spot in the firstphoto-detector element and in the second photo-detector elementrespectively and enters the second objective lens unit; and wherein theposition of the irradiation light converged on the observation object isdetected based on a position of the light spot of the irradiation lightformed in the first photo-detector element and a position of the lightspot of the irradiation light formed in the second photo-detectorelement.
 16. The light spot position detector unit according to claim15, wherein the first direction and the second direction are orthogonalto each other.
 17. The light spot position detector unit according toclaim 15, wherein the first photo-detector element is partitioned in aradial direction, and the second photo-detector element is partitionedin a circumferential direction.
 18. The light spot position detectorunit according to claim 17, wherein the first photo-detector elementincludes light-receiving areas partitioned into concentric circles witha central point coinciding the optical axis of the objective lenssystem, and the second photo-detector element includes sector-formedlight-receiving areas, of which circumferences coincide with acircumference of one of the concentric circles in the firstphoto-detector element having a largest diameter.
 19. The light spotposition detector unit according to claim 13, wherein the photo-detectorunit is disposed orthogonally with respect to the optical axis of theobjective lens system.
 20. The light spot position detector unitaccording to claim 13, wherein the photo-detector unit is formed withphotodiode made of semiconductor, which transmits light therethrough andgenerates electric current from the light.
 21. The light spot positiondetector unit according to claim 13, wherein the first objective lenssystem, the second objective lens system, the first photo-detectorelement, and the second photo-detector element are integrally coupled.22. A confocal probe comprising an optical scanner device whichincludes: a scanning unit, which casts irradiation light emitted from alight source in an arbitrary direction to scan an observation object; anobjective lens system, which converges the irradiation light on theobservation object; and a photo-detector unit, which is disposed on anoptical axis of the objective lens system to have the irradiation lighttransmit therethrough, wherein a position of the irradiation lightconverged on the observation object is detected based on a position of alight spot of the irradiation light transmitting through thephoto-detector unit.
 23. A confocal probe comprising a light spotposition detector unit which includes: an objective lens system, whichconverges irradiation light emitted from a light source on anobservation object; and a photo-detector unit, which is disposed on anoptical axis of the objective lens system to have the irradiation lighttransmit therethrough, wherein a position of the irradiation lightconverged on the observation object is detected based on a position of alight spot of the irradiation light transmitting through thephoto-detector unit.